Compliance with Paracetamol Prescribing Policies at a Sydney Hospital

Drug-induced liver injury in older adults

Drug-induced liver injury (DILI) is an important cause of hospitalisation and of medication deregistration. In old age, susceptibility to DILI is affected by changes in physiology and increased interindividual variability, compounded by an increased prevalence of disease and the frailty syndrome. While dose-related or predictable DILI reactions are often detected in preclinical trials, the occurrence of rare hypersensitivity or idiosyncratic reactions cannot be reliably predicted from preclinical studies or even by clinical trials. The limited participation of older adults in clinical trials means that the susceptibility of this population to DILI is largely unknown. Vigilance during clinical trials and postmarketing surveillance must be universally practised. A systematic approach should be taken to determine not only which medicines are hepatotoxic and should be removed from the market, but also the hepatotoxicity risks from marketed drugs to consumers with different characteristics, many of whom are older people.

Hepatotoxicity of therapeutic short-course paracetamol in hospital inpatients: impact of ageing and frailty

BACKGROUND

Paracetamol, a commonly used simple analgesic, can be fatal in overdose. Case reports suggest liver damage may occur at therapeutic doses. In older and particularly frail patients, dose reduction of therapeutic paracetamol is recommended due to concerns of an increased risk of hepatotoxicity.

AIMS

This study aimed to investigate the effects of ageing and frailty on the safety of paracetamol in hospital inpatients commenced on short courses of the drug.

METHODS

An observational cohort study of young (18-55 years, n = 19), older (≥ 70 years) fit (n = 24) and older frail (n = 28) hospital inpatients. Treatment group participants commenced regular paracetamol (3-4 g/day) during their hospital admission, whereas the control group was not exposed to paracetamol. In both groups, plasma alanine aminotransferase (ALT) was measured at baseline and day 5, and risk factors for raised ALT were recorded. A random serum paracetamol concentration was measured at day 5 in the treatment group.

RESULTS

No older frail treatment participants had an abnormal day 5 ALT. Odds ratios for having a day 5 ALT above the upper limit of normal (ULN) with paracetamol use, compared with unexposed controls, were 3·7 [95% confidence intervals (CI): 0·32, 41·59] for older not frail participants and 2·5 (95% CI: 0·34, 18·3) for younger participants. Decreasing frailty score independently predicted a day 5 ALT above the ULN (P < 0·05). Day 5 serum paracetamol concentrations were highest in older frail participants (P < 0·005).

CONCLUSION

Higher paracetamol concentrations observed in frail older patients after 5 days of therapeutic paracetamol do not necessarily indicate an increased risk of hepatotoxicity.